How to calculate the optimal thickness

Hello,

I want to calculate optimal thickness from this program, and I did not how to do it.

Please I need your help,

clear all;
clc;
lambda=1.55e-6;
n1=input('introduire l''indice optique n1 ');
n2=input('introduire l''indice optique n2 ');
n3=input('introduire l''indice optique n3 ');
d=linspace(0,500e-9,100);
R=(((n1*n3-n2^2)^2*sin((2*pi/lambda)*n2*d).^2+n2^2*(n3-n1)^2*cos((2*pi/lambda)*n2*d).^2)./((n1*n3+n2^2)^2*sin((2*pi/lambda)*n2*d).^2+n2^2*(n3+n1)^2*cos((2*pi/lambda)*n2*d).^2));
plot(d,R)
title('R=f(d)');
xlabel('d(m)');
ylabel('R');

[Shubham Gupta]

which variable is thinkness? Is it n1, n2, n3, R, d, lambda ? Also, optimal thickness to achieve what? There should be a target to get the optimal value to achieve that target.

Let us know more about the problem and the process by which you have approched this problem, maybe we can help with your process if you are stuck somewhere.

[MAROUANE ENNAGADI]

Hello,

n1=1, n2=2, n3=1,

After I traced the graph, I want to determine tickness optimal from this graphe.

[Adam Danz]

What is d(m) and R and how do we use these data to determine thickness? What do you consider to be optimal?

Answer 1

[Ridwan Alam]

Assuming, optimal thickness yields maximum refraction,

m = find(R==max(R))
optimal_thickness = d(m)

% ans =
%   1.9192e-07

[MAROUANE ENNAGADI]

Thanks you so much.

But when I changed the parametrs:

n1=1; % n1_Si3N4
n2=1.98; % n2_AlInAs
n3=3.21; % n3_AIInAs

I found optimal_thickness=0